Carotid MR angiography using pulsed continuous arterial spin labeling

Introduction Carotid artery disease is a major cause of cerebral ischemia and infarction. It is routinely assessed using contrast-enhanced magnetic resonance angiography (MRA). Several methods for nonenhanced MRA exist, which may be particularly advantageous in patients with impaired renal function due to the risk of nephrogenic systemic fibrosis. Pulsed arterial spin-labeled (ASL) MRA has been investigated for carotid MRA, however, the signal to noise ratio (SNR) with the method is problematic when short repetition times are used to minimize scan time or when long labeling times are used to maximize visible vessel length. In contrast to pulsed ASL (PASL), we hypothesized that pulsed continuous ASL (PCASL) would provide improved SNR at short repetition times and/or long labeling durations.